Atlas of 2D metals epitaxial to SiC: filling-controlled gapping conditions and alloying rules

TL;DR

This study uses high-throughput first-principles calculations to predict the structures, stability, and electronic properties of all metals intercalated between graphene and SiC, revealing new gapping mechanisms and alloying rules for 2D metals.

Contribution

It provides a comprehensive computational survey of 2D metals on SiC, uncovering trends, gapping conditions, and alloying rules that expand the understanding of 2D metallic materials.

Findings

Agreement with known experimental structures

Identification of metal-specific gapping mechanisms

Derivation of alloying rules for 2D metals

Abstract

The realization of air-stable 2D metals epitaxial to SiC and capped by graphene creates a potentially immense chemical space of 2D metals and alloys that could expand the variety of solid-state excitations unique to 2D metals beyond what is known for graphene and niobium/tantalum chalcogenides. We perform a high-throughput computational survey from first-principles predicting the structures and stabilities of all metals in the periodic table when they intercalate graphene/SiC. Our results not only agrees with all experimentally known metal/SiC structures explored so far, but also reveals conspicuous trends related to metal cohesive energies and metal-silicon bonding. For special groups of metals, a small bandgap opens, relying on appropriate electron filling and substrate-induced symmetry breaking. From this gapping stabilization, we derive alloying rules unique to 2D metals.